Graphene-constructed flower-like porous Co(OH)2 with tunable hierarchical morphologies for supercapacitors

Abstract

Graphene-constructed flower-like porous Co(OH)₂ (GFC) composites were prepared using a one-pot hydrothermal process. The flower-like porous Co(OH)₂ with a hierarchical structure was perfectly constructed using graphene sheets. This strategy facilitated the large-scale synthesis of GFC composites. The morphologies of Co(OH)₂ ranged from flower petals to large flower-like microspheres. The morphologies were easily controlled by changing the weight ratio of graphene oxide to cobalt salt. The flowers were approximately 5–10 μm in diameter and composed of numerous thin nanoplates. The GFC, as an electrode material for supercapacitors, showed a high specific capacitance of 480 F g⁻¹ at 1 A g⁻¹ and outstanding cycling performance with 93.5% capacitance retained over 1000 cycles. The outstanding electrochemical performance of GFC could be attributed to the large specific surface area of the GFC and synergistic interaction between uniformly dispersed Co(OH)₂ and graphene.